Source : Webster's Revised Unabridged Dictionary (1913)

Oligarchy \Ol"i*gar"chy\, n.; pl. {Oligarchies}. [Gr. ?; ? few,
   little + ? to rule, govern: cf.F. oligarchie.]
   A form of government in which the supreme power is placed in
   the hands of a few persons; also, those who form the ruling
   few.

         All oligarchies, wherein a few men domineer, do what
         they list.                               --Burton.

Source : WordNet®

oligarchy
     n : a political system governed by a few people